Coolant jackets may be provided in both cylinder heads and cylinder blocks of internal combustion engine to provide cooling to the engine. EP 0 038 556 B1, for example, describes a cooling system for an internal combustion engine. Coolant is conveyed through a cylinder head coolant jacket via a first pump. A second pump conveys coolant through the cylinder block coolant jacket. The cylinder head coolant jacket and the cylinder block coolant jacket are not connected within the internal combustion engine. However, the outlets of the cylinder block and cylinder head coolant jackets are connected in a main coolant circuit line. A cooler bypass line system branches off from the main coolant circuit line. The cooler bypass line is connected to an inlet of both the cylinder head coolant jacket and the cylinder block coolant jacket. A control valve may prevent coolant flow to a cooler positioned in the main coolant circuit line and permit flow through the cooler bypass line system. A second control valve may be used to interrupt or adjust a coolant flow through the cylinder block coolant jacket.
To provide a more integrated design, in some internal combustion engines the cylinder block and the cylinder head may be traversed in each case separately from one another by coolant in their respective coolant circuits. In other words, the coolant may flow through the engine in a parallel configuration such that one coolant circuit flows though the cylinder head and another coolant circuit flows through the cylinder block. This cooling arrangement may be referred to as a split cooling system. In this way, the cylinder head, which is thermally coupled to a combustion chamber wall and the exhaust-gas conducting arrangement, and the cylinder block, which is thermally coupled to friction components as well as other components, can be separately cooled. The aim of split cooling system is to provide cooling to the cylinder head in the warm-up phase of the internal combustion engine and prevent cooling to the cylinder block in the warm-up phase. As a result, the cylinder block can be brought up to a desired operating temperature more quickly. Preventing coolant flow to the cylinder block may be referred to as a no flow strategy.
EP 1 900 919 A1 discloses an engine with this type of split cooling system. Specifically EP 1 900 919 A1 discloses a split coolant circuit in an internal combustion engine in which a cylinder head coolant jacket and a cylinder block coolant jacket are provided. The split coolant circuit includes a pump, a cooler, a thermostat and a heating arrangement (e.g., heat exchanger). The split coolant circuit may be configured to circulate coolant therethrough. The thermostat is arranged so as to control the flow of the coolant both through the cylinder block coolant jacket and through the cooler when the coolant exceeds a predefined temperature. The split cooling design enables the engine oil, the engine coolant, and/or the cylinder liners of the pistons to be heated more quickly. As a result, engine friction and emissions during cold starting conditions may be decreased.
The Inventors herein have recognized several drawbacks to this type of split coolant circuit. For example, if a vehicle occupant were to request cabin heating during the engine warm-up phase, engine coolant may be directed through the cylinder block and to the heater core thereby increasing engine warm-up time. Accordingly, engine emissions and fuel consumption may be increased during such conditions.
As such in one approach, an internal combustion engine is provided. The internal combustion engine includes a cylinder block including a cylinder block coolant jacket and a cylinder head including an outlet-side cylinder head coolant jacket having an exhaust-gas collector integrated therein, the cylinder head coupled to the cylinder block to form at least one combustion chamber and the outlet-side cylinder head coolant jacket including at least one coolant passage adjacent to the exhaust-gas collector. The internal combustion engine further includes a coolant pump fluidly coupled to the cylinder block coolant jacket and the outlet-side cylinder head coolant circuit and a control system configured to, during a portion of a warm-up phase, flow coolant through an outlet-side cylinder head coolant jacket and inhibit coolant flow through the cylinder block coolant jacket. In this way, coolant flow may be inhibited to the cylinder block during certain warm-up enabling the engine block to reach a desired operating temperature more quickly.
Further in some examples, the outlet-side cylinder head coolant jacket is fluidly coupled to a cabin heating arrangement and the control system is further configured to, during a portion of a warm-up phase, flow coolant from the outlet-side cylinder head coolant jacket to the cabin heating arrangement. In this way, heat may be provided to a cabin of the vehicle during warm-up while at the same time enabling the cylinder block to reach a desired operating temperature more quickly by substantially inhibiting flow of coolant into the cylinder block coolant jacket.
This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Furthermore, the claimed subject matter is not limited to implementations that solve any or all disadvantages noted in any part of this disclosure.